1. Field of Invention
The present invention relates generally to a semiconductor substrate processing apparatus. More specifically, the invention relates to an apparatus for dissipating energy from a device coupled to semiconductor processing chamber.
2. Background of the Invention
In plasma processing of semiconductor substrates, certain processing steps require the regulation of chamber pressures and removal of gases and process residues from a processing chamber. Typically, pressure regulation and the removal of such gases and process residues are facilitated through the use of a vacuum pumping system and throttle valve coupled to an exhaust port in the processing chamber. Generally, some pumping systems include a large turbomolecular pump.
FIG. 1 depicts an exemplary semiconductor substrate processing system 100 of the prior art having a throttle valve 158 and turbomolecular pump 160. An example of such a chamber is described by Collins in U.S. Pat. No. 5,707,486, issued Jan. 13, 1998.
The processing system 100 comprises a process chamber 110 having a bottom 126, sidewalls 124, and a lid 122 that define a chamber volume 112. A substrate support pedestal 118 is disposed in the process chamber 110 and supports a workpiece or substrate 120 (i.e., a wafer). Generally, at least one gas supply 142 is coupled to the process chamber 110 via one or more ports positioned either in the lid 122 or sidewalls 124. The gas supply 142 provides process and other gases to a processing region 114 of the chamber volume 112 above the substrate 120.
The chamber volume 112 is evacuated via a pumping system 170 coupled to an exhaust port 136 disposed in the sidewall 124 of the process chamber 110. Generally, the pumping system 170 comprises a gate valve 156 and a turbomolecular pump 160. Typically, the gate valve 156 is coupled to the exhaust port 136. The turbomolecular pump 160 is coupled to the gate valve 156. Typically, the gate valve 156 is used to isolate the turbomolecular pump 160 when the pump is not in use. Generally, to reach and maintain processing conditions, the turbomolecular pump 160 is activated to generate and maintain a low or vacuum pressure within the chamber volume 112. Pressure is regulated within the process chamber 110 by actuating a throttle valve 158 disposed between the process chamber 110 and the turbomolecular pump 160, typically at the interface between the process chamber 110 and the exhaust port 136.
As turbomolecular pumps operate at high rotational speeds, the momentum of these devices can be large. When these devices fail, energy is transferred to both the process plumbing and chamber (or intermediate components) to which the pump is mounted. For example, a 2000 liters/second turbomolecular pump used in some processing chambers may generate a deceleration torque of about 60,000 Nm that must be absorbed by the processing chamber if the pump should fail. If this energy is not effectively absorbed by the processing chamber upon pump failure, the chamber to which the pump is mounted may become damaged beyond repair. Chamber failure can result in excessive and costly down time as the failed chamber typically must be removed and replaced by a new chamber. Chamber replacement of this type can result in unplanned loss of factory capacity and late fulfillment of production orders.
Moreover, as higher volume pumps are being developed and utilized in process chambers in order to meet demands for increased wafer throughput, the increased pump energies used to generate the higher flow rates require chambers to be able to absorb even greater amounts of energy in the advent of pump failure. Many existing chambers simply can not accommodate the high energies generated in during pump failure when retrofitted with a higher volume pump.
Therefore, there is a need for an apparatus for coupling a device to a semiconductor processing chamber that can dissipate the energy associated with device failure.
An apparatus and method for coupling a device to a processing chamber is provided. Generally, the apparatus comprises a first ring, a second ring, and an energy dissipation ring disposed between the first ring and the second ring. In one embodiment of the invention, the energy dissipation ring deforms when urged against a blade of the first ring when torque in excess of a predetermined amount is applied.
In another embodiment, an apparatus for coupling a device to a processing chamber includes a first ring and an energy dissipation ring disposed proximate the first ring. A loading means biases the device against the energy dissipation ring.
In another aspect of the invention, a method for dissipating rotational energy is disclosed. In one embodiment, the method comprises urging a first ring to rotate relative to a second ring; and deforming a material between the first ring and the second ring to allow rotation.